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Judge Aaron Persky has been heavily criticised for sentencing Brock Turner to only six months in jail

More than a million people have signed a petition calling for the judge in the controversial Stanford University sexual assault case to be sacked.

Judge Aaron Persky has been heavily criticised for giving student Brock Turner six months for assaulting an unconscious woman last year.

Two other petitions have reached 115,000 and 175,000 signatures each.

The petitions have no legal force but organisers hope they will increase pressure on politicians to act.

Mr Persky, a Superior Court judge in Santa Clara County, California, has reportedly received death threats in the wake of the case.

The jail sentence he handed down to Turner has been widely criticised as too lenient. Prosecutors had called for six years.

Turner was seen by two other students sexually assaulting his victim, now 23, behind an outdoor rubbish bin.

He tried to flee the scene but was caught and later admitted to the assault in court.

Rights activists and members of the general public have accused Mr Persky of being influenced by Turner's upbringing in a wealthy, white family, and his achievements as a college swimmer.

The petition, posted on Change.org, says that Mr Persky had "failed to send the message that sexual assault is against the law regardless of social class, race, gender or other factors".

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Brock Turner was seen by two witnesses sexually assaulting an unconscious woman

The judge said in his remarks that he was concerned about the "severe impact" a longer sentence would have on Turner's life.

Turner's father was also criticised after issuing a statement to the court saying his son was paying a steep price for only "20 minutes of action".

Turner, who was a promising swimmer expected to compete for the US at Olympic level, has been banned for life by USA Swimming, the governing body for professional swimming in the US.

The victim, who has not been named by the press, read an impact statement in court which was later read by millions.

US Vice-President Joe Biden, who is involved in a campaign against campus assaults, wrote her an open letter praising her for her courage and saying he was "filled with furious anger" at the course of events.

The cast of the TV show Girls have also made a video backing the woman and other victims of sexual assault.